Highly sensitive SPR refractive index sensor based on twisted dual side-hole optical fiber

In this study, we developed a twisted optical fiber surface plasma resonance (SPR) refractive index sensor using the helical structure of a dual side-hole fiber (DSHF) to measure refractive index sensitivity. The sensor structure consists of the helical DSHF integrated into a single-mode fiber (SMF) and a multimode fiber (MMF). Our experimental findings demonstrate that the twisted SPR refractive index sensor based on the helical DSHF exhibits excellent responsiveness within the refractive index range of 1.33 to 1.38, with a sensitivity of 1998.09 nm/RIU and a high linear correlation coefficient of 0.9571. This helical DSHF design offers numerous advantages, including high sensitivity, remarkable linearity, a wide measurement range, and ease of manufacturing.